The present invention relates to the use of a screw cartridge and magazine for automatic loading of screw fasteners into an electric screwdriver or similar rotary tool.
The use of electric drills and electric screwdrivers in driving and removing screw-type fasteners has increased in recent years because of their speed and convenience. Their use in the commercial construction industry has not been as widely accepted because of the lack of tools which incorporate a means of storing and automatically feeding the fasteners into the tool. For example, it is widely recognized that screws are preferred over nails in attaching drywall or sheet rock, yet the latter fastener is used more often, because they have been faster to use.
A number of mechanisms for automatic feeding of screw fasteners have been described in the prior art. For example, U.S. Pat. No. 3,757,407 discloses a screw magazine that is attachable to an electric drill. However, it is not readily adaptable to screws of varying sizes, and it requires multiple adjustments for proper positioning and orientation of the fasteners in front of the driving bit.
Similarly, the devices described in U.S. Pat. Nos. 3,907,014 and 3,526,257 involve complex mechanisms to orient the screws properly for use.
U.S. Pat. No. 3,812,961, issued to J. I. Merrick, et al., discloses a screw package but not separable screw cartridges mounted within a self-contained screw cartridge magazine. Although this prior art seeks to allow a convenient method of providing access to plural screws, flexibility was not provided.
U.S. Pat. No. 4,478,212, issued to A. D. Moulton, discloses a fastener feeder that is fixedly attached to the top of a standard drill. This prior art seems specifically intended for industrial use in its complexity and probable expense. The Moulton feeder provides for loading of fasteners only through a clip placed in magazine portion of feeder. Also, holder can not be used independently from feeder.
U.S. Pat. No. 3,891,014 issued to D. T. Gunn for a power screwdriver and U.S. Pat. No. 4,047,611 issued to H. I. Damratowski for an air-powered self-feeding screw driving tool disclose prior attempts to provide auto-feed screw fasteners for principally industrial use. The screw packages disclosed cannot be used independently of the two respective feeders.
West German Patent No. 2,027,642 issued to C. Fein, et al., discloses an automatic feeder specifically intended for strips of screw fasteners. The Fein disclosure provides a single loading orifice, thereby preventing use with a single screw.
U.S. Pat. No. 2,777,484 issued to G. S. Groneman discloses a power operated screw driving attachment. The Groneman device discloses a single method of loading screws through an elongated slot.
What is needed, then, is a simple and inexpensive mechanism for storing and automatic feeding of screws in an electric screwdriver that can easily be used with a wide variety of screws without the need for additional adjustment, attachments, or alignment mechanisms.
It is therefore an object of the present invention to provide a simpler and less expensive cartridge and magazine apparatus for storage and automatic feed of screw fasteners.
It is a further object of the present invention to provide an automatic-feeding screwdriver that can be used without a continuous strip of screw fasteners.
It is still a further object of the present invention to provide an automatic-feeding screwdriver with multiple loading orifices to be used for the loading of single as well as plural screw fasteners.
It is a further object of the present invention to provide a disposable cylindrical cartridge that is as long or longer than the screw that it contains and held in place by a rupturable membrane that would facilitate the driving of self-tapping screws by a power screwdriver with or without an automatic feed.
Still a further object of the present invention is to provide an automatic-feeding screwdriver that does not require fixed attachment to the drill or rotary machine.
A still further object of the present invention is to provide a screw fastener cartridge that is inexpensive to produce and reusable.